Process of making tetra-alkyl lead



tion.

ture. We prefer, however,

Patented Nov. 27, 1928.

UNITED. STATES 1,692,926 PATENT OFFICE.

WILLIAM S. CALCOTT, 01's IEN'NS GROVE, AND HERBERT W. DAUDT, OF CARNEYS POINT, NEW JERSEY, ASSIGNOBS TO E. I. DU IPONT DE NEMOUBS & COMPANY, OF WILMIE'G'I 'ON, DELAWARE, A CORPOBATION OF DELAWARE.

BRQGESS OF MAKING TETRA-ALKYD LEAD.

No Drawing.

This invention relates to animprovement in the production of tetra-alkyl lead and more particularly to the production of such a compound by the action of alkyl chlorides 5 on sodium lead alloys.

A process for producing tetra-alkyl lead by the action of alkyl chlorides on sodium lead alloys at temperatures above the normal cently developed in which the components are caused to react at atmospheric pressure and at temperatures at or below the refluxing 2 temperature of the reaction mass.

An object of our present invention is to more closely control the temperature and pressure conditions by having more liquid present duringthe greaterpart of the reacthe development of a procedure involvlng the progressive addition of the alloy to the alkyl chloride, the latter being held at a definite temperature inanautoclave. The success of this procedure has de ended upon the ability to feed the alloy to t e alkyl chloride with the whole system under the same pressure, This step has, imturn, been accomplished by means of a new. eparture, that of maintaining the alloy hopper at such a temperature that any alkylchloride contained therein, reacts ver slowly, if at all, with the alloy. This may e' accomp lished by maintaining thehopper at a very low tempera to heat the hopper toa temperature such chloride contained therein is entirely. converted' to the vapor phase. Preferably a temperature difference of approximately 50 C. is maintained between the hopper and the autoclave. The'exact difierence is, however, of little importance, the conditlons to water jacketed autoclave, which is provided This object has been accomplishedby that y alkyl tillation 1n the usual manner. 1

Application 11166 October 15, 1927 Serial No. 226,514.

tially no liquid alkyl chloride shall'be present in the hopper, and that the temperature of the latter shall not be raised so high as to produce destructive reaction between the alloy and the alkyl chloride. In this conditlon thealkyl chloride reacts very slowly, if at all, withthe alloy. The high temperature of the alloy is maintained by surrounding the hopper'with a steam jacket. The alloy may be fed from the hop er by means of a worm feed, or other suita le means.

Unless precautions are observed to prevent the'action of the alkyl chloride on the alloy in the hopper, the process would be inoperative, for the reason that the alloy would become spongyand it would be impossible to feed it in a satisfactory manner. In the procedures given below as examples ofour invention, the following equipment may be used: I

A steam jacketed hopper is attached to a with the usual stirring equipment, pressure gauge and safety release valves. The hoper 1s provided with a worm feed by means of which the alloy is fed into the autoclave.

Ewmnple A.

Place 2000 parts of alloy, containing approximately 10% sodium and'90% lead, in the hopper; tighten the cover securely, and turn on 15-20 lbs. steam in the jacket. Feed 1800 parts of ethyl chloride into the autoclave, and, after closing all valves, raise'its temperature to C. While maintaining this temperature, gradually add the alloy over a period of 2-4 hours. Subsequently, maintain the same temperature for 4 hours.

Cool the charge to 30? C. and distill the excess ethyl chloride into suitable condensing equipment, by means of which it may be recovered. Drown the charge in 3000 parts of water and recover the tetra-ethyllead by steam dis-v Example Place 2000 parts of .alloy containing ap- .proximately 10% sodium and 90% lead in the hopper, tighten cover securely, and turn on 15-20 lbs. of steam into the. jacket. Feed 0 becomplied with being merely that substan- 800 parts of kerosene and 560 parts of ethylchloride into the autoclave, and, after closing all valves, raise the temperature to 80 CL While maintaining this temperature, gradually add the alloy over a period of 2-3 hours;

subsequently hold this temperature for 4" hours.

Cool the charge to 2025 C. and extract the tetra-ethyl lead with gasoline.

While we have described the process as specifically appliedto the preparation of tetraethyl lead, it is applicable as well to the preparation of other tetra-alkyl lead compounds from the corresponding alkyl chlorides.

Although the alloy which we prefer to usev is the 10% sodium; alloy which has been known to give the best results in processes heretofore disclosed, the procedure disclosed by us is also applicable to the use of other alloys of lead and sodium.

Our procedure is also applicable to the pressureless process described in copending,

' application of H. W. Daudt, Serial No. 226,-

be used with small variation in yield.

and favorable results may be obtained with temperatures as high as 110 C., but we have found that temperatures of 50 C. to 100 C..

are most satisfactory and these limits may To go much below 50 C. there is danger of delayed reaction.

We have also found that with the use of the potassium bearing alloys temperatures as low as 20 C. can be advantageously used.

Our process has a number of distinct ad: vantages over processes previously known. In our. process, the whole operation can be run at one definite temperature. We find that we can run anentire charge with a.

variation of less than 2 in temperature and] of 5 lbs. in pressure. With processes heretofore known this is impossible. Without the use of solvents the pressure is approximately the same as the average of those obtained in normal runs by theolder process. With the use of solvents this pressure can be reduced from the approximately 60-90 lbs. To'approximately 30-50 lbs. at the temperatures usually employed.

The use of a solvent is desirable in our process, but in processes of the prior art it may be dangerous, because the buildin up of a high enough concentration of ethyl chloride for the starting of the reaction may without departing from the spirit thereof, it

is to be understood that we do not intend to limit ourselves to the specific embodiments thereof except as indicated in the appended claims.

We claim:

1. In the process of making tetra-alkyl lead from a lead alkali metal alloy and an alkyl. chloride, the improvement which comprises the progressive addition of the alloy to the alkyl chloride. I

2. In the process of making tetra-alkyl lead from a lead alkali metal alloy and an alkyl chloride, the improvement which comprises the progressive addition of the alloy to the alkyl chloride, under such conditions that the rate of addition of the alloy is the primary factor in determining the progress of the reaction.

3. In the process of making tetra-alkyl lead by the reaction between a lead alkali metal alloy and an alkyl chloride at substantially atmospheric pressure, the improvement which comprises the progressive addition of the alloy to the alkyl chloride, under such conditions that the rate of addition of the alloy is the primary factor in determining the progress of the reaction.

4:. In the process of making tetra-alkyl lead by the reaction between a lead alkali metal alloy andan alkyl chloride at elevated pressures, the improvement which comprises the progressive addition of the alloy to the alkyl chloride, under such conditions that the rate of addition of the alloy is the primary factor in determining the progress of the reaction. e

5. In the process of making tetra-alkyl lead from a lead alkali metal alloy and an alkyl chloride, the improvement which comprises the progressive addition of the .alloy to the alkyl chloride, the alloy being fed from a hopper wherein it is maintained under. such temperature conditionsthat substantially no reaction takes place between it and any alkyl chloride which may be present in the hopper.

6. In the process of making tetra-alkyl lead by the reaction between a lead alkali metal alloy and an alkyl chloride under pressure, the improvement which comprises the progressiveaddit-ion of the alloyto the alkyl chloride, the alloy being. fed from a hopper wherein it is maintained under such temperature conditions that little or -no reaction takes place between it and any alkyl chloride which may be present in the hopper.

7. In the process of making tetra-alkyl lead from a lead alkali metal alloy and an alkyl chloride, the improvement which comprises the progressive addition of the alloy to the alkyl chloride, the alloy being fed from a I chloride, the alloy being fed from ahopper which is maintained at such a temperature that any alkyl chloride contained therein is substantially all converted to the vapor phase.

9. In the process of making tetra-alkyl lead from a lead alkali metal alloy and an alkyl chloride in the presence of a diluent, the .im-

provement which comprises the progre sive addition of the alloy to the alkyl chloric e.

10. In the process of making tetra-alkyl lead from a lead-alkali metal alloy and an alkyl chloride in the presence of a diluent, the improvement which comprises the progressive addition of the alloy to the'alkyl chloride, the alloy being fedfrom a hopper which is maintained at such a temperature that any alkyl chloride contained therein is Substantially all converted to the vapor phase.

11. In the process of making tetra-ethyl I lead from a lead alkali metal alloy and ethyl chloride, the improvement which comprises the progressive addition of the alloy to the ethyl chloride.

12. In the process of making tetra-ethyl lead from a lead alkali metal alloy and ethyl chloride, the improvement which comprises the progressive addition of the alloy to the ethyl chloride under such conditions that the rate of addition. of the alloy is the primary factor in determining the progress of the reaction. p

13. In the process of making tetra-ethyl lead by the reaction between-a lead alkali metal alloy and ethyl chloride at substan tially atmospheric pressure, the improvement which comprises the progressive addition of the alloy to the ethyl chloride under such conditions that the rate .of addition of the alloy is the primary factor in determining the progress of the reaction,

14. In the process of making tetra-ethyl lead'b-y the reaction between a lead alkali metal alloy and ethyl chloride at elevated pressures, the improvement'whicli comprises the progressive addition of the alloy tothe ethyl chlor de under such conditions that the rate of addition of the alloy is the primary factor in determining the progress of the reaction.

15. In the process of making tetra-ethyl lead from a lead alkali metal alloy and ethyl chloride, the improvement which comprises the progressive addition of the alloy to the ethyl chloride, the alloy being. fed from a hopper wherein it is maintained under such temperature conditions that little or no re action takes place between it and any ethyl chloride which may be present in the hopper.

16. In the process of making tetra-ethyl lead from a lead alkali metal alloy and ethyl chloride, the improvement which comprises the progressiveaddition of the alloy to the ethyl chloride, the alloy being fed from a hopper which is maintained at-such a'temperature thatany ethyl chloride contained therein is substantially all-converted to the,

vapor phase. I

17. In the process of making tetra-ethyl lead by the reaction between-a lead alkali metal alloy and ethyl chloride under pressure, the improvement which comprises the progressive addition of the alloy to the ethyl chloride, the alloy being fed from a hopper that any ethyl chloride contained therein is substantially all converted to the vapor phase. I 18. In the process of making tetra-ethyl lead from alead alkali metal alloy and ethyl chloride, in the presenceof a diluent, the im-' provement which comprises the progressive addition of the alloy to the ethyl chloride.

19. In the process of making tetra-ethyl lead from a lead alkali metal alloy and ethyl chloride, in the presence of a diluent, the improvement which comprises the progressive addition of the alloy to the ethyl chloride, the alloy being fed from a hopper which is maintained at such a temperature that any alkyl chloride contained therein is substantially all converted to the vapor phase.

20. Inthe process of making tetra-ethyl lead by the reaction between a lead alkali metal alloy and ethyl chloride under pressure, in the presence of a diluent, the improvement which comprises the progressive addition of the alloy to the ethyl chloride, the alloy being fed from a hopper which is maintained at sucha temperature that any alkyl chloride contained therein issubstantially all converted to thevapor phase.

21. In the process of making tetra-ethyl lead from a lead-sodium alloy and ethyl chloride, the improvement which comprises the progressive addition of the alloy to the ethyl chloride. 1

22. In the process of making tetra-ethyl lead from an alloy of lead, sodium, and potassium, and ethyl chloride, the improvement which comprises the progressive addiwhich is maintained at such atemperature I tained at such a temperature that any ethyl lead from an alloy of lead, sodium and potas- 10 chloride contained therein is substantially slum, and ethyl chloride, in the presence of all converted to the vapor phase. a diluent, the improvement which comprises 24. In the .process of making tetra-ethyl the progressive addition of the alloy to the 5 lead from a lead-sodium alloy and ethyl chloethyl chloride.

ride in the presence of a diluent, the improve- In testimony whereof we affizi our signa- 15 ,ment which comprises the progressive additures.

tion of the alloy to the ethyl chloride. l/VILLIAM S. CALCOTT.

25. In the process of making tetra-ethyl HERBERTW. DAUDT. 

